Polymeric substances comprising the reaction product of melamine, aldehyde and oxazolidines

ABSTRACT

Prepolymeric resinous compositions from an oxazolidine and melamine and a lower aliphatic aldehyde. The resinous compositions polymerize on heating and have utility in baking enamels and in electrodeposition formulations to increase the solvent resistance of the film.

United States Patent 11 1 1111 3,725,350 Hunsucker [4 1 Apr. 3, 1973 [54] POLYMERIC SUBSTANCES [58] Field of Search ..260/67.5, 67.6 R

COMPRISING THE REACTION PRODUCT OF MELAMINE, ALDEHYDE [56] References Cited AND OXAZOLIDINES UNITED STATES PATENTS [761 Invent: Jmy Cmnme" 2,448,890 9/1948 Johnston ..260/307 clal Soluents Corp Terra Hallie 2,517,128 8/1950 Meunieretal. ..2oo/o7.5 Ind. 47808 [22] Filed: AP 26 1972 Primary Examine rHoward E. Schain Att0mey-Howard E. Post et al. [21] Appl. No.: 247,680

Related us. Application Data [57] ABSTRACT Prepolymeric resinous compositions from an ox- [63] fgy f 'z g Of May azolidine and melamine and a lower aliphatic alan one dehyd'e. The resinous compositions polymerize on heating and have utility in baking enamels and in elec- [52] Cl H7/128'4 7/132 trodeposition formulations to increase the solvent re- 117/155 L, 117/161 LN, 260/29.4 R, 260/67.6 R Int. Cl. ..C08g 9/30 sistance of the film.

10 Claims, No Drawings POLYMERIC SUBSTANCES COMPRISING THE REACTION PRODUCT OF MELAMINE, ALDEHYDE AND OXAZOLIDINES CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of U.S. Ser. No. 36,679, filed May 12, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to polymeric substances. In a particular aspect, this invention relates to polymeric, resinous products useful in baking enamels and electrodeposition formulations.

Oxazolidines (including mono-oxazolidines and the bicyclo-aza-dioxo-octanes) have been known from the time of Senkus, J. Am. Chem. Soc., 67, 1515-1559 (1945). William B. Johnston, U.S. Pat. No. 2,448,890, disclosed reacting bicyclic oxazolidines with fatty acids to yield esters, which had the properties of drying oils.

Baking enamels applied by spraying and dipping are well known coating materials that are used in large quantities but the industry is ever in need of improvements in these compositions relative to improved flexibility, improved adhesion to metal substrates, resisting corrosion of the metal substrates, improved drying rate, as well as improvements in many of the other important properties.

Another class of coatings that have come into more recent widespread uses are electrodeposition resins wherein a substrate is immersed inan aqueous dispersion of the resin, an electric current is passed through the medium and the resin is deposited upon the substrate. The resinous coating is then baked'to achieve the desired properties. These coatings have tended to suffer from some of the same disadvantages as the earlier baking enamels and consequently there exists a need for improving them.

SUMMARY OF THE INVENTION Other objects will be apparent to those skilled in the art from the disclosure herein.

It has been discovered that improved baking enamels and formulations for electrodepositions are obtained by reacting a monocyclic oxazolidine corresponding to the formula wherein R is hydrogen or an alkyl group of one to three carbon atoms or a bicyclic oxazolidine corresponding to the formula CII2O (ll) where R is hydrogen, methyl, ethyl, hydroxymethyl or the group 1 wherein R is a saturated or unsaturated aliphatic hydrocarbon group of from 1 to 21 carbon atoms and R has the same meaning defined above, with melamine and a lower aliphatic aldehyde, by mixing the ingredients and heating under reflux for a length of time sufficient to form the prepolymeric resinous composition.

DETAILED DISCUSSION The resinous composition of the present invention includes the condensation product of an Oxazolidine corresponding to the foregoing formulas I or II with melamine and a lower aliphatic aldehyde. The condensation is effected by heating a mixture of the reactants at reflux temperature, i.e., at from about 95 C to about 1 10 C, for about 1 to 3 hours.

, In preparing the melamine-oxazolidine-formaldehyde resinous compositions, a mole ratio of about 1.5-2.5 moles of oxazolidine are used per mole of melamine, and about 1 to 2 moles of aldehyde are employed per mole of melamine. The reaction is conducted in the presence of a lower alkyl alcohol having from one to four carbon atoms.

The resinous compositions of the present invention are hard, clear, colorless and solvent resistant when baked at a temperature and for a length of time suitable to effect complete polymerization, e.g., at about 350F for from 10 to 15 minutes, yet they are not brittle. They are suitable for use as the vehicle in baking enamels and paper coatings. They can be readily dispersed in water with suitable dispersing agents, many of which are known, and are especially useful in coatings applied by electrodeposition.

Some of the oxazolidines used in the practice of this invention are commercially available and the usual commercial materials are suitable. 4,4-Dime'thyloxazolidine is generally known as Oxazolidine A and this designation is employed in the examples. The bicyclic Oxazolidine wherein R is ethyl is known as Oxazolidine E and this designation is used in the examples. The bicyclic oxazolidine wherein R is hydroxymethyl is known as Oxazolidine T and this designation'is used in the Examples. Other oxazolidines, i.e., esters thereof and those made from aldehydes other than formaldehyde, can be made by the method of M. Senkus or Wm. B. Johnson.

Aliphatic aldehydes useful in preparing the compositions include the lower aliphatic aldehydes of from one to four carbon atoms, e.g., formaldehyde, acetal dehyde, propionaldehyde, and nand iso-butyraldehyde. These materials are commercially available and the usual commercial materials are suitable.

The melamine used in the practice of this invention is commercially available and the usual commercial material is suitable.

The invention will be better understood with reference to the following examples. It is understood, however, that these examples are intended as illustrations only and are not to be considered as limiting the invention.

EXAMPLE 1 A resin was formed by mixing the following ingredients in a reaction vessel equipped with a thermometer, stirrer, reflux condenser and take-off head:

Melamine (1 mole) 126 g Oxazolidine E (1.5 mole) 214 Formaldehyde (162 g of 37% aqueous 60 solution, 2 mole) 2-Butanol 210 The solution was heated to reflux temperature, about 94 C, for 2 hours. Water and some of the 2-butanol were then separated by distillation as the azeotrope (95 ml) over a period of about 45 minutes. It was allowed to cool to room temperature and the properties were determined. A wet film, 1.5 mil thick, was drawn down on a standard steel Q panel and was then baked. Properties of the solution and of the baked film are given in the table.

EXAMPLEZ The experiment of Example 1 was repeated except that the following ingredients were used:

Melamine (1 mole) 126 g Oxazolidine E (2.5 moles) 357 Water 200 Formaldehyde (81 g of 37% solution) 30 Reflux temperature was about 140 C and water was removed over a period of 1 hour after a previous 2 hour reaction period. A wet film of 1% mil thickness was drawn down on a standard steel Q panel and was then baked. Properties of the solution and of the baked film are given in the table.

TABLE Summary of Results Example No. 1 2 Properties of Soln. Color, Gardner 1 2 Viscosity, Gardner J Solids Content 55%+ Baking temp., "F 350 350 Baking time, min. Properties of Film Film hardness 6H 6H Flexibility, passes A Reverse impact, lb. 10

EXAMPLE 3 The experiment of Example 1 is repeated except that Oxazolidine T is substituted for Oxazolidine E on an equi-molar basis. The resulting resinous composition is useful in baked coatings.

EXAMPLE 4 The experiment of Example 1 is repeated except that Oxazolidine A is substituted for Oxazolidine E on a 2:1 molar basis. The resulting resinous composition is useful in baked coatings.

EXAMPLE 5 The experiment of Example 1 is repeated except that acetaldehyde is substituted for formaldehyde on an equi-molar basis. The resulting resinous composition is useful in baked coatings.

EXAMPLE 6 The experiment of Example 1 is repeated except that propionaldehyde is substituted for formaldehyde on an equi-molar basis. The resulting resinous composition is useful in baked coatings.

EXAMPLE 7 The experiment of Example 1 is repeated except that n-butyraldehyde is substituted for formaldehyde on an equi-molar basis. The resulting resinous composition is useful in baked coatings.

EXAMPLE 8 The experiment of Example 1 is repeated except that iso-butyraldehyde is substituted for formaldehyde on an equi-molar basis. The resulting resinous composition is useful in baked coatings.

EXAMPLE 9 The experiment of Example 1 is repeated except that 2 moles of 4,4-dimethyloxazolidine is substituted for Oxazolidine E. The resulting resinous composition is useful in baked coatings.

EXAMPLE 10 The acetate ester of Oxazolidine T is prepared in accordance with the method of Danielson, US. Pat. No. 3,256,137. The experiment of Example 1 is repeated in all essential details except that the resulting Oxazolidine T acetate is substituted for Oxazolidine E on an equi-molar basis. The resulting resinous composition is useful in baked coatings.

EXAMPLE 1 l The lauric acid ester of Oxazolidine T was prepared as follows:

Oxazolidine T, g (1 product mole) was charged to a one-liter flask equipped with an agitator, thermometer and a decanter head mounted on an 18 inch Vigreaux distillation column. Lauric acid, 200 g (1 mole) and 15 ml benzene were added and the mixture was heated to C for 2 hours after which time the esterification was judged to be complete as indicated by removal of about 1 mole of water. The benzene was removed by distillation and the produce was allowed to cool.

The crude product was a red-brown liquid having a neutralization equivalent of 359.2. The infrared spectrum was consistent with that of an Oxazolidine having an ester linkage (absorption peak at 1735 cm).

A portion of the crude Oxazolidine ester was recrystallized from methanol yielding a white crystalline product having the following properties:

Found Expected Neutral equivalent 341 327 Acid No. 2.9 none Saponification No. 166.3 171 N, 4.16 4.28 C, b 66.07 66.0 H, 9.97 10.1 Melting point 33-34C EXAMPLE 12 Oxazolidine T is esterified with behenic acid in accordance with Example 11. The experiment of Example l is repeated in all essential details except that the resulting Oxazolidine T behenate is substituted for Oxazolidine E on an equi-molar basis. The resulting resinous composition is useful in baked coatings.

EXAMPLE 13 The oxazolidine wherein R of formula I is methyl is prepared by reacting 2-amino-2-methyl-l-propanol with acetaldehyde according to the method of M. Senkus, cited hereinbefore. The oxazolidine thereby obtained is substituted on an equi-molar basis for Oxazolidine E in Example 1, which is repeated in all essential details.

EXAMPLE 14 The experiment of Example 2 is repeated in all essential details except that in place of Oxazolidine E, there is substituted on an equi-molar basis, the oxazolidine corresponding to formula [I obtained by reacting 2- amino-2-methyl-l, 3-propanediol with butyraldehyde according to the method of Senkus hereinbefore cited.

1 claim:

1. A prepolymer resinous composition comprising the condensation product of an oxazolidine with melamine and an aliphatic aldehyde of from one to four carbon atoms, said oxazolidine corresponding to the formula:

CHR'

wherein R is hydrogen or an alkyl group of one to three carbon atoms, or corresponding to the formula:

wherein R is hydrogen, methyl, ethyl, hydroxymethyl where R is hydrogen, methyl, ethyl or hydroxymethyl.

5. The composition of claim 1 wherein said aldehyde is acetaldehyde.

6. The composition of claim 1 wherein said aldehyde is propionaldehyde.

7. The composition of claim 1 wherein said aldehyde is n-butyraldehyde.

8. The composition of claim 1 wherein said aldehyde is iso-butyraldehyde.

9. The composition of claim 4 wherein R is methyl.

10. The composition of claim 4 wherein R is ethyl. 

2. The composition of claim 1 wherein said aldehyde is formaldehyde.
 3. The composition of claim 1 wherein said oxazolidine is 4,4-dimethyloxazolidine.
 4. The composition of claim 1 wherein said oxazolidine corresponds to the formula
 5. The composition of claim 1 wherein said aldehyde is acetaldehyde.
 6. The composition of claim 1 wherein said aldehyde is propionaldehyde.
 7. The composition of claim 1 wherein said aldehyde is n-butyraldehyde.
 8. The composition of claim 1 wherein said aldehyde is iso-butyraldehyde.
 9. The composition of claim 4 wherein R is methyl.
 10. The composition of claim 4 wherein R is ethyl. 